We wouldn’t think that RFID antennas are all that important while setting up an AIDC system. However, unknown to most of us, picking out the right antenna can be the difference between success and disaster. But how will you know which type of antenna is suitable for your needs? For that, you need to know the distinct types of antennas available in the market and how an RFID antenna works.
So, that is exactly what I'll help you understand today. Don’t worry, it won’t feel like a lecture.
What is an RFID Antenna?
A radio frequency identification system has three major components, namely – RFID Tags, Readers, and Antennas. The tag contains information regarding the items, the reader is responsible for interrogating and decrypting the signal from the tags and sending it to the system, and the antenna is responsible for facilitating the communication between the above two.
To elaborate, an RFID antenna acts as a transceiver. The antenna broadcasts the reader’s signal to create an interrogation zone, the tag uses the signals inside this zone to send back the encoded data. The antenna then receives the signals and sends them to the reader for processing.
How does an RFID Antenna Work? Working Principle behind an RFID Antenna
Electromagnetic propagation is the basic principle that we use to explain the functioning of the antenna. According to the laws of electromotive induction, any circuit carrying a charge will create a magnetic field around it. Inside an antenna, when you induce electric current in an antenna, the current travels along it at a specific frequency. The moving electrons are oscillating and create a disturbance. This disturbance is passed along and moves through space, these are known as radio waves.
On the other end of the process is another antenna (RFID Reader Antenna). This antenna when encountering a radio wave will have the electrons inside it disturbed. The electrons will start oscillating in the frequency of the radio signal, inducing a current of the same frequency which is read by the RFID reader and converted into readable information.
Different Types of RFID Antennas
Due to the vast applications, we have developed different types of RFID antennae, suitable for different applications. There are many ways to classify antenna types based on factors like operational frequency, type of polarization, and Portability.
Based on magnetic field, there are Far-Field RFID Antenna and Near-field Antennas as well the only difference being the coverage.
So, let’s discuss them all.
This is the most common way that people in the industry classify RFID antennae. The polarity of an antenna refers to the orientation in which the radio waves travel from the antenna. There are two types of antenna types based on polarization.
(A). Linear Polarization
These types of antennae propagate radio waves that travel along a single plane, hence the name linear. They have a higher input power to range ratio, in other words, they have higher Gain.
(B). Circular Polarization
On the other hand, circular polarization antennae have signals that travel in a cork/helix pattern along the antenna surface. This means the signals can travel along multiple planes, but this means that they also have less Gain (range) as compared to linear ones.
(A). Low Frequency
These antennae usually operate at 125 to 134.2 kHz of radio waves. These waves usually propagate close to the ground and have a low rate of data transfer. The benefit of these types of antennae is, that they require less power to work and are immune to disturbances from metal surfaces.
(B). High Frequency
As the name suggests, these antennae have a higher operating frequency than LF antennae. These have a broadcast frequency of around 13.5 MHz. Like LF antennae, these can withstand the effect of metal surfaces, but they also have a better range and transmitting rate.
(C). Ultra-High Frequency
These are the most used antenna types in most industries due to their high transfer speed. They operate at 850 – 960 MHz frequency range. They also have the highest broadcast range; however, they also require a considerable amount of energy compared to an LF antenna.
RFID Antennas types: Portability
Based on the mounting method, the portability of an RFID antenna can differ and their applications.
These antennas are attached at a stationary position, they are connected to the reader through cables. Being connected to a continuous power supply, these antennas are capable of broadcasting powerful signals. This provides them with a good communication range.
These types of antennas are generally attached to a handheld/portable reader. They are powered by the internal battery of the reader. Their portability covers for their lack of read range. Unlike mounted antennae, they are not used along a moving automated line, but rather in situations where employees have to carry a reader within a facility.
These antennas are integrated into a reader. In short, traditional RFID systems have separate readers and antennae that are connected via cables. However, these antennas are a part of the reader. They are easier to install and move around; however, they do not have the same coverage range as traditional antennas.
Although we may not pay enough attention or importance to antennae, they are a very essential part of all forms of communication technology throughout the world. Without antennae, it would be impossible to conduct long-distance communication. You can find an antenna in things as big as a radar to as small as an RFID inlay.
Due to their wide applications, we have developed many different types of these devices for different industries & applications. There are many things that one needs to keep in mind while choosing an antenna, namely – Frequency, Input Power, Polarization, Gain, etc.
Frequently Asked Questions
Q1. What antenna is used in RFID?
Ans - For radio frequency identification, we generally use short-range linear or circular polarization antenna, that operate from 125 KHz to 960 MHz frequency range.
Q2. What is the range of an RFID antenna?
Ans - The range of an RFID antenna can differ based on several factors like Input Power, Gain Factor, Frequency, and type of RFID Tag. Depending on these, an antenna can have a read range from a few centimeters to a little more than 100 meters.
Q3. Can RFID detect distance?
Ans - No, although much like cellular towers and GPS, RFID also works on the communication of information using radio signals, they cannot detect distance. This is because an RFID antenna is its unit, and does not communicate with each other. To clarify, to detect distance, a system must be capable of triangulating a signal, which is not possible with RFID.